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IGERT Affiliate Examines Mold Growth on Green Building Materials
Achievement/Results
Recently, there has been a rapid increase in the marketing and utilization of green building materials in response to rising energy costs and concerns over global warming and indoor air quality. While the resistance of conventional materials to mold growth has been investigated, the susceptibility of green building materials remains virtually unstudied. To address this need, Chi Hoang, a doctoral candidate participating as an affiliate in the National Science Foundation’s (NSF) Integrative Graduate Education and Research Traineeship (IGERT) program in Indoor Environmental Science and Engineering at The University of Texas at Austin (UT) has evaluated the mold susceptibility of selected green building materials used in ceiling tiles, flooring, drywall and cabinetry. Chi compared the resistance of the green materials and their conventional counterparts to colonization by common indoor mold following water saturation and/or exposure to high humidity conditions. Such conditions are commonly encountered following plumbing leaks, flooding events or even during periods of high humidity that occur in many areas of the United States.
The results of her mold resistance experiments suggest that the green materials evaluated in this study were not necessarily more resistant, nor more prone, to mold growth than were their non-green counterparts. However, cellulose-rich, organic-based, materials were much more susceptible to mold growth than were inorganic materials for both green and non-green building materials. Interestingly, mold growth on the top surface and sides of the some materials could be quite different for heterogeneous materials. Direct wetting of building materials was found to speed up mold growth although extended exposure to high humidity conditions eventually led to significant mold growth as well. To conduct her evaluations, Chi developed an image processing method to quantify the rate and extent that mold covers the surfaces of a given building material. This analysis yielded mold growth rates that can be incorporated into building environment models to estimate the impact of moisture intrusion events. She also introduced the concept of T50%, the time it takes for mold to cover 50% of a given material surface, as a simple metric for comparing the relative resistance of different building materials to mold colonization. Finally, she determined that the presence of external nutrients promotes the growth of fungi indicating that when clean building materials get “dirty” over time, they are much more susceptible to mold growth.
This novel research represents an interdisciplinary effort of Chi Hoang and IGERT faculty participants Kerry Kinney and Richard Corsi in Environmental Engineering and Dr. Paul Szaniszlo in Molecular Genetics & Microbiology. Chi’s work with green building materials has already led to one publication (on the reactivity of green building materials to ozone) and a second paper on the mold susceptibility of green building materials has been submitted. She is also preparing a third paper which will compare the relative “greenness” of building materials with respect to their mold resistivity, ozone reactivity and byproduct emission rates. Chi’s success in the IGERT program is all the more extraordinary in that she participated in the IGERT program as an Affiliate (an international student who is not an official, NSF-funded trainee but who nevertheless participates in all program events). Chi’s doctoral research was funded instead by the Vietnam Education Foundation. Following graduation this May, Chi will continue her research on building materials as a post doctoral fellow working on a project funded by the National Institute of Standards and Technology (NIST).
Address Goals
To our knowledge, Chi Hoang is the first to examine the chemical reactivity and mold susceptibility of green building materials (discovery). Despite the popularity of these materials, there is virtually no scientific definition of “green” building materials and Chi’s work is laying the foundation for a rational rating of different building materials. Particularly for bio-based green materials, it is important to understand if these materials are suitable for locations where they will be exposed to moisture. Chi’s efforts led to a close interdisciplinary collaboration between a mycologist (fungal expert) and engineers studying the built environment (learning). Since Chi is from Vietnam, she also provided an invaluable international perspective to the research.
